Some of the most enjoyable music was with a system i had with a Cary SLP 93 preamp, Cary SLM 100 mono blocks (100wpc) and ProAc response 2.5's. Probably 9 years ago now when I had all that. Proac's and tube just seem to gel the best imo. You should really try a tube amp IMO.
Also like was mentioned tube rolling in Cary gear is quite effective. I also ran NOS Mullards in my preamp and they are fantastic tubes.
The 89db of the ProAc's is not that bad as they are a tube friendly load. I had success with 60wpc, 100wpc and even a 40wpc tube amps with my old 2,5's